fix(asset): avoid redownload and add asset version

src/duobench/__init__.py

@@ -5,17 +5,41 @@
 
 import numpy as np
 import rcs
-from rcs import get_prefix
+from rcs import download_assets, get_prefix
 from rcs._core import common
 
 DUOBENCH_GITHUB_ASSET_ARCHIVE_URL = "https://github.com/RobotControlStack/duobench/archive/refs/tags/{tag}.zip"
+# written after a complete download, marks which duobench version the assets belong to
+ASSETS_VERSION_FILE = Path("assets/.duobench_version")
 
-DUOBENCH_PREFIX = get_prefix(
+
+def _download_assets(version: str, prefix: Path, github_asset_archive_url: str, assets_dirname: str) -> None:
+    download_assets(version, prefix, github_asset_archive_url, assets_dirname)
+    (prefix / ASSETS_VERSION_FILE).write_text(version)
+
+
+def _get_duobench_prefix(env_prefix: str | None, editable_prefix: Path, default_prefix: Path) -> str:
+    # rcs.get_prefix checks for an RCS asset that is not part of the duobench archive, so it would
+    # re-download the duobench assets on every import; skip it if the assets of this version are there
+    if env_prefix or not (editable_prefix.resolve() / "assets").is_dir():
+        prefix = Path(env_prefix).expanduser().resolve() if env_prefix else default_prefix.resolve()
+        version_file = prefix / ASSETS_VERSION_FILE
+        if version_file.is_file() and version_file.read_text() == __version__:
+            return str(prefix)
+    return get_prefix(
+        env_prefix,
+        editable_prefix,
+        default_prefix,
+        __version__,
+        DUOBENCH_GITHUB_ASSET_ARCHIVE_URL,
+        download_fn=_download_assets,
+    )
+
+
+DUOBENCH_PREFIX = _get_duobench_prefix(
     os.environ.get("DUOBENCH_PREFIX"),
     Path(__file__).resolve().parents[2],
     Path.home() / ".duobench",
-    __version__,
-    DUOBENCH_GITHUB_ASSET_ARCHIVE_URL,
 )
 
 CAMERA_PATHS: dict[str, str] = {}

src/tests/test_asset_prefix.py

@@ -0,0 +1,48 @@
+from pathlib import Path
+
+import pytest
+
+import duobench
+
+
+@pytest.fixture()
+def downloads(monkeypatch: pytest.MonkeyPatch) -> list[Path]:
+    calls: list[Path] = []
+
+    def fake_download(_version: str, prefix: Path, _url: str, assets_dirname: str) -> None:
+        calls.append(prefix)
+        (prefix / assets_dirname).mkdir(parents=True, exist_ok=True)
+
+    monkeypatch.setattr(duobench, "download_assets", fake_download)
+    return calls
+
+
+def test_assets_downloaded_once(tmp_path: Path, downloads: list[Path]):
+    prefix = tmp_path / "prefix"
+    for _ in range(3):
+        assert duobench._get_duobench_prefix(str(prefix), tmp_path / "pkg", tmp_path / "default") == str(prefix)
+    assert downloads == [prefix]
+    assert (prefix / duobench.ASSETS_VERSION_FILE).read_text() == duobench.__version__
+
+
+def test_default_prefix_used_without_env(tmp_path: Path, downloads: list[Path]):
+    default = tmp_path / "default"
+    for _ in range(2):
+        assert duobench._get_duobench_prefix(None, tmp_path / "pkg", default) == str(default)
+    assert downloads == [default]
+
+
+def test_assets_redownloaded_on_version_change(tmp_path: Path, downloads: list[Path]):
+    prefix = tmp_path / "prefix"
+    (prefix / "assets").mkdir(parents=True)
+    (prefix / duobench.ASSETS_VERSION_FILE).write_text("0.0.0")
+    duobench._get_duobench_prefix(str(prefix), tmp_path / "pkg", tmp_path / "default")
+    assert downloads == [prefix]
+    assert (prefix / duobench.ASSETS_VERSION_FILE).read_text() == duobench.__version__
+
+
+def test_editable_install_skips_download(tmp_path: Path, downloads: list[Path]):
+    editable = tmp_path / "pkg"
+    (editable / "assets").mkdir(parents=True)
+    assert duobench._get_duobench_prefix(None, editable, tmp_path / "default") == str(editable)
+    assert downloads == []